Not every bug on the clean-up crew is an insect. Pill bugs and sowbugs are crustaceans, so they are more closely related to crabs and shrimp than to beetles, and pill bugs can roll into a ball while sowbugs cannot. Springtails have six legs like insects, but scientists now place them in a separate group, though they were once counted as an order of insects. Today they are usually classed as entognathous hexapods, a sister group of the insects.

Springtails are easy to overlook, but there are a lot of them. Most live in soil and eat fungi, algae, rotting plants and bacteria, although a few hunt tiny soil animals. They breathe through their skin, so they need damp places, and millipedes need damp air too, which is why they hide under leaves, logs and stones. In moist soil that is rich in rotting plant matter, springtails can number in the thousands per square foot.

Dung beetles fall into groups by what they do with dung. Dwellers live and breed in the dung, and tunnellers drag it underground and lay their eggs in brood balls made from it. Rollers shape it into balls and roll it away, while stealers take the brood balls other beetles made. The groups show that dung beetles do not all deal with a dung pile in the same way.

How do we know dung beetles and their insect neighbors matter? South Dakota researchers tested it by caging some dung pats to keep insects out and leaving others open. The caged pats broke down much more slowly, so the insects were doing real work. Without such helpers, a pile of cow dung can sit in a field for a very long time and smother the grass under it.

Leafcutter ants work on a huge scale. In South America, a big leafcutter colony eats about as much fresh plant material each day as a cow, and the ants in it would weigh about as much as a cow. Only some ants farm, and all the fungus-farming ants live in the New World, mostly in the tropics of Central and South America.

A fungus garden needs constant care. The ants chew leaf pieces into tiny bits before they add them to the garden, and fungus-farming ants must guard it from other molds and bacteria. A Smithsonian scientist says an ant visits every square centimeter of the garden every few seconds. When a young queen starts a new nest, she carries a piece of the fungus garden in her mouth.

Black soldier fly larvae eat rotting food scraps, and what they leave behind is good for soil. They give off heat as they eat and speed up decay, and they can also reduce germs and some harmful residues in the waste they eat. Adult black soldier flies do not bite.

Food waste is a large number. As of January 2025, about 40 percent of food made for people in the United States never gets eaten. Black soldier fly larvae are one way to turn some of that waste into soil booster and animal feed, because the larvae turn waste into frass, which farmers can use to boost soil.

Termites do their own clean-up work in forests. They break down fallen trees and stumps and let their nutrients go back into the soil, and they eat the soft part of the wood grain first and leave the harder part. Most termites cannot digest wood alone, because tiny one-celled protists in a termite's gut help turn wood into food for the colony. Termites are social insects, and a colony has workers, soldiers, and kings and queens, with the queens laying the eggs.

In a compost pile, tiny living things and small bugs eat old leaves and food scraps and turn them into dark brown compost. The pile gets warm while it works, and the heat comes from the tiny living things that are eating inside it. Bacteria work first and their numbers jump. When the pile cools, centipedes, millipedes, sowbugs and earthworms carry on the work.

Soil is full of earthworms and other small animals. There are on average 100 to 500 earthworms in each square meter of soil, and worms make up a large share of the weight of soil animals. Healthy soil teems with life. A single teaspoon can hold more living things than there are people on Earth, and a USDA scientist says all the soil life in one acre equals about two African elephants in weight.

Words to know

• crustaceans: crab-like animals
• tunnellers: diggers of tunnels
• protists: tiny one-celled life
• larvae: young bugs
• compost: rotted plant mix